In contrast to fast and slow skeletal muscle cells that fuse and terminally differentiate, smooth muscle cells are able to simultaneously proliferate and express lineage-restricted proteins. One of these proteins, expressed exclusively in smooth muscles, has been referred to as SM22-alpha, a 22-kD protein with structural similarity to the vertebrate thin filament myofibrillar regulatory protein calponin and the Drosophila muscle protein mp20, neither of which play a direct role in the contractile apparatus.
NCBI Summary:
This gene encodes a shape change and transformation sensitive actin-binding protein which belongs to the calponin family. It is ubiquitously expressed in vascular and visceral smooth muscle, and is an early marker of smooth muscle differentiation. The encoded protein is thought to be involved in calcium-independent smooth muscle contraction. It acts as a tumor suppressor, and the loss of its expression is an early event in cell transformation and the development of some tumors, coinciding with cellular plasticity. The encoded protein has a domain architecture consisting of an N-terminal calponin homology (CH) domain and a C-terminal calponin-like (CLIK) domain. Mice with a knockout of the orthologous gene are viable and fertile but their vascular smooth muscle cells exhibit alterations in the distribution of the actin filament and changes in cytoskeletal organization. [provided by RefSeq, Aug 2017]
General function
Actin binding
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Cellular localization
Cytoplasmic
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Ovarian function
Steroid metabolism
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miR-133b targets tagln2 and functions in tilapia oogenesis. Ma Z et al. (2021) microRNAs (miRNAs) are important components of non-coding RNAs that participate in diverse life activities by regulating gene expression at the post transcriptional level through base complementary pairing with 3'UTRs of target mRNAs. miR-133b is a member of the miR-133 family, which play important roles in muscle differentiation and tumorigenesis. Recently, miR-133b was reported to affect estrogen synthesis by targeting foxl2 in mouse, while its role in fish reproduction remains to be elucidated. In the present study, we isolated the complete sequence of miR-133b, which was highly expressed in tilapia ovary at 30 and 90 dah (days after hatching) and subsequently decreased at 120 to 150 dah by qPCR. Interestingly, only a few oogonia were remained in the antagomir-133b treated tilapia ovary, while phase I and II oocytes were observed in the ovaries of the control group. Unexpectedly, the expression of foxl2 and cyp19a1a, as well as estradiol levels in serum were increased in the treated group. Furthermore, tagln2, an important factor for oogenesis, was predicted as the target gene of miR-133b, which was confirmed by dual luciferase reporter vector experiments. miR-133b and tagln2 were co-expressed in tilapia ovaries. Taken together, miR-133b may be involved in the early oogenesis of tilapia by regulating tagln2 expression. This study enriches the understanding of miR-133b function during oogenesis and lays a foundation for further study of the regulatory network during oogenesis.//////////////////
Expression regulated by
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Ovarian localization
Cumulus, Granulosa
Comment
This gene was found in a rat ovarian cDNA library (Unigene)